The present invention relates to elevator systems, and more particularly to elevator systems without a separate machineroom.
A typical traction elevator system includes a car and a counterweight disposed in a hoistway, a plurality of ropes that interconnect the car and counterweight, and a machine having a traction sheave engaged with the ropes. The ropes, and thereby the car and counterweight, are driven by rotation of the traction sheave. The machine, and its associated electronic equipment, along with peripheral elevator components, such as a governor, are housed in a separate machineroom located above, adjacent or proximate to the hoistway.
A recent trend in the elevator industry is to eliminate the separate machineroom and locate the various elevator equipment and components in an expanded hoistway. An example is JP 4-50297, which discloses the use of a machine located between the car travel space and a wall of the hoistway. The embodiment disclosed in this document requires the cross-sectional area of the hoistway to be expanded in order to fit the machine.
Another example of such an elevator is U.S. Pat. No. 5,429,211, which discloses the use of a machine located in the same position but having a motor with a disc-type rotor. This configuration makes use of the flatness of such a machine to minimize the expansion of the cross-sectional space needed for the machine in the hoistway. These types of machines, however, are limited to relatively low duties and low speeds.
In practice, these types of elevators also require a vertical extension of the hoistway in order to fit the machine and other equipment. Both of these configurations can add to the construction cost of installing the elevator system. In addition, placing the machine and other typical machineroom equipment in the hoistway requires special procedures and precautions to be taken in order to service the equipment.
The above art notwithstanding, scientists and engineers under the direction of Applicants"" Assignee are working to develop elevator systems that efficiently utilize the available space within a building.
According to one embodiment of the present invention, an elevator system includes a hoistway having a vertically adjacent structural platform that includes a recess, and a machine that fits within the recess. The vertically adjacent structural platform defines either the ceiling or floor of the hoistway.
As a result of having the machine tucked into the recess in the hoistway, the machine is removed from the hoistway and the hoistway need not be expanded, either horizontally or vertically, to accommodate the machine. This reduces the space required for the hoistway to an amount sufficient to accommodate the car, counterweight, guide rails and ropes.
According to a particular embodiment of the present invention, the machine is a traction machine and the elevator system uses flat ropes as the suspension and traction ropes for the car and counterweight. This embodiment is particularly advantageous since the use of flat ropes minimizes the traction sheave diameter and, correspondingly, the size of the machine. In practice, the machine diameter may be in the range of 200-300 mm. Since most roof slabs in buildings have a depth of 200-300 mm, the machine in this embodiment may be fit within a recess in the roof slab in many buildings without requiring an extension above the roof of the building.
A principal feature of the present invention is the use of flat ropes. Flat rope, as used herein, is defined to include ropes having an aspect ratio, defined as the ratio of width w relative to thickness t, substantially greater than one. A more detailed description of an example of such ropes is included in commonly owned co-pending U.S. patent applications Ser. No. 09/031,108, entitled xe2x80x9cTension Member for an Elevatorxe2x80x9d, filed Feb. 26, 1998, and Ser. No. 09/218,990, entitled xe2x80x9cTension Member for an Elevatorxe2x80x9d, filed Dec. 22, 1998, both of which are incorporated herein by reference.
According to a further embodiment of the present invention, the elevator system includes ropes that engage with sheaves on the car such that the ropes pass under the car, and a compact door operator that is disposed below the roof line of the car. This embodiment permits the car to be raised to a height (including minimal safety distances) within the hoistway such that the roof of the car is immediately adjacent to the ceiling of the hoistway. The advantage of this embodiment is that the vertical distance between the top floor landing and the ceiling of the hoistway is minimized. In practice, with a conventional car height of approximately 2.2 meters, the top floor landing to hoistway ceiling distance (hereinafter referred to as xe2x80x9coverheadxe2x80x9d) can be between 2.5 and 2.8 meters. This arrangement provides a further benefit for the design and construction of the building as it permits every floor of the building to be the same height, i.e., 2.5-2.8 meters.